Controlling a time-scaling of an audio signal

Abstract

For controlling a time-scaling of an audio signal, the audio signal being distributed to a sequence of frames that are received via a packet switched network, a change in a delay of received frames is detected. Moreover, an amount of time scaling that is to be applied to received frames for compensating for the detected change is determined. Further, a kind of the change is determined. Further, a length of a time window within which a time scaling of the determined amount is to be completed is determined depending on the determined kind of the change.

Description

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic block diagram of a transmission system according to an embodiment of the invention;

FIG. 2 illustrates details of an audio receiver of the system of FIG. 1;

FIG. 3 illustrates further details of an audio receiver of the system of FIG. 1; and

FIG. 4 is a flow chart illustrating an operation in the audio receiver of FIG. 1.

Claims

1. A method for controlling a time-scaling of an audio signal, said audio signal being distributed to a sequence of frames that are received via a packet switched network, said method comprising: detecting a change in a delay of received frames;determining an amount of time scaling that is to be applied to received frames for compensating for said detected change;determining a kind of said change; anddetermining a length of a time window within which a time scaling of said determined amount is to be completed depending on said determined kind of said change.

2. The method according to claim 1, wherein a determined kind of said change is either a kind requiring a shorter time window for a determined amount of time scaling or a kind permitting a longer time window for a determined amount of time scaling.

3. The method according to claim 2, wherein a kind of a change requiring a shorter time window is determined to be given at least in case one of a change in delay, which change exceeds a predetermined value, and a delay spike is detected.

4. The method according to claim 2, wherein received frames are buffered in a variable buffer upon reception and wherein a kind of a change permitting a longer time window is determined to be given at least in case a gradually changing buffer occupancy is detected.

5. The method according to claim 2, wherein a kind of a change permitting a longer time window is determined to be given at least in case a changed amount of delayed frames is detected.

6. The method according to claim 1, comprising a subsequent step of time scaling received frames by said determined amount within a time window of said determined length.

7. The method according to claim 6, further comprising determining a type of content of said frames within said time window and avoiding a time scaling of those frames within said time window, which frames have a content of a predetermined type.

8. The method according to claim 6, wherein said time-scaling is applied to received frames after a preceding processing of said received frames.

9. The method according to claim 6, wherein received frames are buffered in a variable buffer upon reception and retrieved from said variable buffer for decoding, and wherein frames that are subjected to said time scaling are decoded frames.

10. The method according to claim 6, wherein received frames are buffered in a variable buffer upon reception and retrieved from said variable buffer for decoding, and wherein frames that are subjected to said time scaling are frames including a linear prediction synthesis filter excitation signal generated in said decoding.

11. A chipset with at least one chip, said at least one chip comprising a time scaling control component for controlling a time-scaling of an audio signal, which audio signal is distributed to a sequence of frames that are received via a packet switched network, said time scaling control component being adapted to detect a change in a delay of received frames;said time scaling control component being adapted to determine an amount of time scaling that is to be applied to received frames for compensating for a detected change;said time scaling control component being adapted to determine a kind of a detected change; andsaid time scaling control component being adapted to determine a length of a time window within which a time scaling of said determined amount is to be completed depending on said determined kind of said change.

12. An audio receiver comprising a time scaling control component for controlling a time-scaling of an audio signal, which audio signal is distributed to a sequence of frames that are received via a packet switched network, said time scaling control component being adapted to detect a change in a delay of received frames;said time scaling control component being adapted to determine an amount of time scaling that is to be applied to received frames for compensating for a detected change;said time scaling control component being adapted to determine a kind of a detected change; andsaid time scaling control component being adapted to determine a length of a time window within which a time scaling of said determined amount is to be completed depending on said determined kind of said change.

13. An electronic device comprising a time scaling control component for controlling a time-scaling of an audio signal, which audio signal is distributed to a sequence of frames that are received via a packet switched network, said time scaling control component being adapted to detect a change in a delay of received frames;said time scaling control component being adapted to determine an amount of time scaling that is to be applied to received frames for compensating for a detected change;said time scaling control component being adapted to determine a kind of a detected change; andsaid time scaling control component being adapted to determine a length of a time window within which a time scaling of said determined amount is to be completed depending on said determined kind of said change.

14. The electronic device according to claim 13, wherein a determined kind of said change is either a kind requiring a shorter time window for a determined amount of time scaling or a kind permitting a longer time window for a determined amount of time scaling.

15. The electronic device according to claim 13, said time scaling control component being further adapted to time scale received frames by a determined amount within a time window of a determined length.

16. The electronic device according to claim 15, wherein said time scaling control component is adapted to determine a type of content of frames within said time window and to avoid a time scaling of those frames within said time window, which frames have a content of a predetermined type.

17. A system comprising a packet switched network adapted to transmit audio signals, a transmitter adapted to provide audio signals for transmission via said packet switched network and a receiver adapted to receive audio signals via said packet switched network, said receiver including a time scaling control component for controlling a time-scaling of an audio signal, which audio signal is distributed to a sequence of frames that are received via said packet switched network, said time scaling control component being adapted to detect a change in a delay of received frames;said time scaling control component being adapted to determine an amount of time scaling that is to be applied to received frames for compensating for a detected change;said time scaling control component being adapted to determine a kind of a detected change; andsaid time scaling control component being adapted to determine a length of a time window within which a time scaling of said determined amount is to be completed depending on said determined kind of said change.

18. A software program product in which a software code for controlling a time-scaling of an audio signal is stored, said audio signal being distributed to a sequence of frames that are received via a packet switched network, wherein said software code realizes the following steps when being executed by a processor: detecting a change in a delay of received frames;determining an amount of time scaling that is to be applied to received frames for compensating for said detected change;determining a kind of said change; anddetermining a length of a time window within which a time scaling of said determined amount is to be completed depending on said determined kind of said change.

19. The software program product according to claim 18, wherein a determined kind of said change is either a kind requiring a shorter time window for a determined amount of time scaling or a kind permitting a longer time window for a determined amount of time scaling.

20. The software program product according to claim 18, wherein when being executed by a processor said software code realizes a subsequent step of time scaling received frames by said determined amount within a time window of said determined length.